Primary motility disorders of esophagus

Introduction

Primary motility disorders of the esophagus (Greek: Oesophagus dyskinesia primaria) are a heterogeneous group of diseases characterized by abnormal peristalsis and/or dysfunction of the esophageal sphincters, in the absence of secondary causes such as systemic diseases or structural lesions. These disorders manifest clinically with symptoms such as dysphagia, non-cardiac chest pain, regurgitation, and, less commonly, weight loss or respiratory complications. The advent of high-resolution manometry (HRM) and the Chicago Classification has refined the diagnostic criteria and classification of these entities, enhancing both clinical and research approaches.

Epidemiology

Primary esophageal motility disorders are relatively rare. Achalasia, the most studied entity, has an incidence of approximately 1 per 100,000 individuals per year, with a prevalence of 10 per 100,000. Other disorders, such as distal esophageal spasm (DES) and hypercontractile (jackhammer) esophagus, are even less common, predominantly affecting individuals over 60 years of age. There is no significant gender predilection, and most cases are sporadic, though rare familial forms of achalasia have been described.

Etiology

The etiology of primary esophageal motility disorders remains incompletely understood. Achalasia is associated with degeneration of inhibitory myenteric neurons (Auerbach’s plexus), possibly due to autoimmune, viral, or idiopathic mechanisms. Spastic and hypercontractile disorders are thought to result from impaired inhibitory neural input, leading to uncoordinated or excessive contractions. Genetic predisposition is suspected in rare familial cases, but most cases are idiopathic.

Pathophysiology

  • Achalasia: Characterized by loss of peristalsis in the esophageal body and impaired relaxation of the lower esophageal sphincter (LES), resulting in functional obstruction and progressive esophageal dilation.
  • Distal Esophageal Spasm (DES): Defined by premature, simultaneous contractions in the distal esophagus with normal LES relaxation, leading to non-propulsive motility and intermittent obstruction.
  • Hypercontractile (Jackhammer) Esophagus: Marked by excessively strong, prolonged peristaltic contractions (distal contractile integral [DCI] > 8000 mmHg·s·cm) with normal timing and LES relaxation.
  • Absent Contractility: Complete loss of peristalsis with preserved LES relaxation, often associated with systemic sclerosis but can be idiopathic.

Signs and Symptoms

  • Dysphagia (solids and liquids)
  • Non-cardiac chest pain
  • Regurgitation of undigested food (especially in achalasia)
  • Weight loss (advanced achalasia)
  • Respiratory symptoms (aspiration, nocturnal cough)
  • Heartburn and odynophagia (less common)

Diagnostics

  • High-Resolution Manometry (HRM): Gold standard for diagnosis, allowing precise characterization of motility patterns and sphincter function according to the Chicago Classification (v4.0).
  • Barium Esophagogram: May show classic “bird-beak” appearance in achalasia or corkscrew esophagus in DES.
  • Upper Endoscopy: Excludes structural lesions and pseudoachalasia (e.g., malignancy).
  • Functional Lumen Imaging Probe (FLIP): Assesses esophageal distensibility and contractility.

Differential Diagnoses

  • Secondary motility disorders: Scleroderma, diabetes mellitus, Chagas disease, amyloidosis, myopathies.
  • Mechanical obstruction: Esophageal carcinoma, peptic strictures, eosinophilic esophagitis.
  • Functional esophageal disorders: Functional dysphagia, globus sensation.

Therapeutic Options

  • Achalasia:
    • Pneumatic dilation (Level 1 evidence)
    • Laparoscopic Heller myotomy with partial fundoplication (Level 1)
    • Peroral endoscopic myotomy (POEM) (Level 1)
    • Botulinum toxin injection (Level 2, for high-risk patients)
    • Pharmacotherapy (nitrates, calcium channel blockers; limited efficacy)
  • Distal Esophageal Spasm and Hypercontractile Esophagus:
    • Smooth muscle relaxants (calcium channel blockers, nitrates; Level 2)
    • Tricyclic antidepressants (for chest pain; Level 2)
    • Botulinum toxin injection (Level 2)
    • POEM (emerging evidence, Level 2)
    • Esophagectomy (rare, for refractory cases)
  • Absent Contractility:
    • Symptomatic management (dietary modification, prokinetics; limited efficacy)
    • Treatment of underlying systemic disease (if present)

Prognostic Factors

  • Achalasia: Prognosis is generally favorable with appropriate intervention, though risk of esophageal dilation, aspiration, and, rarely, squamous cell carcinoma increases with delayed diagnosis.
  • Spastic and Hypercontractile Disorders: Typically non-progressive, but symptoms may be refractory to therapy.
  • Absent Contractility: Prognosis depends on underlying etiology; idiopathic cases have limited therapeutic options, while secondary forms may improve with treatment of the primary disease.
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